I mean you can buy it here in a normal store. So I'm not sure if you mean a dentist can't use/provide it, or if you're thinking about the nano forms of it.
Edit, just saw this:
the FDA regulates dental products like toothpaste as cosmetics rather than therapeutic agents for cavity prevention
Interestingly, many ingredients used in dental care, including fluoride, are employed off-label. This means they are used in ways not officially approved by the FDA but are still considered effective based on scientific evidence and clinical practice
Seems a bit odd to have so much standard, correct-era tech. Having anachronism seems like the point, the futurism bit. Like Quadrilateral Cowboy, or often Cowboy Bebop.
The one exception may be the stuff like that Nissan 300ZX (1985) digital dashboard, that feels anachronistic in an entirely different way. I could imagine a 3hr video essay on how expensive the design was, or perhaps a Technology Connections breakdown of the functionality/workings/issues etc.